The floppy disk or diskette is a well-known device for storage and retrieval of electronic data. The disk is typically a plastic such as Mylar polyester film, with a diameter of approximately 20 cm and a thickness of approximately 0.08 mm, having at its center a drive hole. It is permanently enclosed in and supported by a jacket of stiff paper or plastic. The jacket has two openings: a central opening corresponding to the drive hole and a radial opening through which the disk recording surface is exposed to a transducer or read/write head.
The disk and jacket together form a disk cartridge adapted for mounting in a disk drive mechanism. The disk is rotated in the mechanism while the jacket is stationary. The head, positioned over the jacket radial opening in contact with the disk surface, is movable radially thereof. In practice, disk cartridges are used interchangeably in one disk drive mechanism, with each cartridge inserted and removed many times. It is therefore desirable that insertion and removal be accomplished easily, without damage to the disk and at a minimum of contamination from dust particles and the like.
It has been found advantageous to include means in a disk drive mechanism to aid initial positioning and removal of a disk. U.S. Pat. No. 4,040,107 to Bryer granted Aug. 2, 1977, shows a cam operated positioning and ejection control. A simpler control means including a spring-loaded ejector is found in a recording apparatus for vehicles disclosed in U.S. Pat. No. 3,281,854 to Fiehn granted Oct. 25, 1966. The principle is applied to disk drives in U.S. Pat. No. 3,940,793 to Bleiman granted Feb. 24, 1976, wherein a spring-mounted ejector member is engaged by the leading edge of a disk cartridge and, upon complete insertion, urges the cartridge trailing edge against a positioning surface. U.S. Pat. No. 3,890,643 to Dalziel granted June 17, 1975 shows a cartridge loading apparatus in which an ejector mechanism is cocked upon cartridge insertion slightly farther than is necessary for centering. As the apparatus is closed following insertion, camming surfaces force the cartridge into the centered position.
These structures, while aiding the insertion and ejection of a cartridge, can interfere with disk centering, driving, or both. The ejector mechanisms of Feihn and Bleiman contact the cartridge throughout operation, and thus can interfere with disk rotation and centering if not accurately machined. The Dalziel device depends upon movement of the cartridge relative to the loading apparatus as it is closed. Consequently rapid closure may cause premature clamping of the disk before it is centered.